General Description of Pattern Generation
It is common practice to generate patterns on photosensitive surfaces or layer on workpieces by means of pattern generators such as laser direct writers and mask writers. Different kinds of patterns for different applications are generated in this manner, for example patterns on workpieces in the form of substrates for manufacturing printed circuit boards, patterns on workpieces for manufacturing displays or patterns on workpieces for manufacturing a photomask.
In the example of manufacturing printed circuit boards an electric circuit pattern is generated in order to couple connection points or contact pads of components such as dies in a desired electric circuit. The expression die is herein used as common expression for any electronic component such as a passive component, an active component, or any other component associated with electronics.
Such a pattern is generated in a photolithography process in which an image of a circuit pattern is projected or printed on a photosensitive surface layer by an exposure system exposing light onto the photosensitive surface in a certain pattern. Dependent on the used kind of photosensitive surface material, unexposed or exposed parts of the photosensitive surface layer are removed to form etching masks on the workpiece. The masked workpiece is then etched to form the desired pattern on a layer beneath the photosensitive surface. A variation of this concept is to use the pattern on the photosensitive surface to deposit material onto the underlying layer, e.g. to form an electrical circuit pattern or connection points on the workpiece in the case of printed circuit boards.
Pattern Generator
The pattern generator is, as mentioned above, for example realized by means of a laser direct imaging (LDI) system devised for writing a pattern on the photosensitive surface by means of a laser scanning the surface with a laser beam that is modulated according to image pattern data and forming an image representing a desired pattern. Another kind of pattern generator is a mask writer or a stepper. Commonly, a pattern is designed as an image in a CAD system and control of the pattern generator is based on image pattern data.